Pneumatically operated closed chest cardiac compressor



1968 c. E. BARKALOW $36 PNEUMATICALLY OPERATED CLOSED CHEST CARDIACCOMPRESSOR Filed Nov. 9, 1964 4 Sheets-Sheet 1 uummmmmmu //0IIHIIIIIIIIIIHIHIHI IHIHHHHHllllHlHi 1663 IIIHIHIIIIHIH HHH ATTORNEYS NVENTOR.

1958 c. E. BARKALOW PNEUMATICALLY OPERATED CLOSED CHEST CARDIACCOMPRESSOR 4 Sheets-Sheet 2 Filed Nov. 9, 1964 INVENTOR. (2/2/65 A.54/6694 01d BY M? 77/72 Kszcouos/ ATTORNEYS Jan- 23, 19 c. E. BARKALOWPNEUMATICALLY OPERATED CLOSED CHEST CARDIAC COMPRESSOR Filed Nov. 9,1964 4 Sheets-Sheet Z INVENTOR. CZAWZ i EAAAWZd/ ATTORNEYS Jan. 23, 1968c. E. BARKALOW 4 Sheets-Sheet 4 Filed NOV. 9, 1964 NNN NNN

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- INVENTOR. 644/66 5. 545mm ATTORNEYS United States Patent Ofiice3,364,924 Patented Jan. 23, 1968 3,364,924 PNEUMATICALLY OPERATED CLOSEDCHEST CARDIAC COMPRESSOR Clare E. Barkalow, Comstock Park, Mich,assignor to Michigan Instruments, Incorporated, Cornstock Park,

Mich, a corporation of Michigan Filed Nov. 9, 1964, Ser. No. 409,634 23Claims. (Cl. 128-53) ABSTRACT OF THE DISCLOSURE A cardiac compressorhaving a base with a support platform adapted to be placed under apatient and a compressor unit being rigidly attached to said base suchthat when in operation, it reciprocates vertically over the patient. Thecompressor unit is attached to a support column and with the compressor,forms a unit which snaps in place on the platform. Rigid engaging meansare provided on the support platform and the supporting column forcooperative engagement. Preferably, an, overhanging flange on theplatform engages a plate at the base of the column and there is providedmeans to snap said base into locking engagement with said column.

The compression cylinder contains a reciprocatable plunger which hasthereon means to indicate the extent of external deflection.

A pressure operated system is provided to control the reciprocationcycle and the operation of the compressor. Means are further providedfor controlled build-up of pressure in the compressor unit and snapaction release of pressure during the return cycle of the reciprocatableplunger.

This invention relates to cardiac compressors, and more particularly toa pneumatically operated external cardiac compressor for emergency use.

A person whose heart has stopped beating normally has also stoppedbreathing. Cardiopulmonary resuscitation is needed within 20-30 secondsat most. This necessitates constant cyclic ventilation of the patientfor oxygenation, and concomitant, constant, cyclic, forced pumping ofblood from the heart for perfusion. Compression of the heart by externalcompression for a time period (systole) is followed by its expansion fora time period (diastole).

An external cardiac compressor must operate with a constant, cyclicforce pulse to externally compress the heart by depression of thebreastbone, and thereby, force blood out of the heart and through thepatients system. The pulse interval sometimes is taken in response toheart signals caused by weak contractions of the heart itself, usingelectrical pick-offs to detect the signal. More frequently, however, theheart is compressed on an externally controlled time interval. Onemethod of controlling this time interval is with an electrical signalgenerating, pulse type, power supply to activate the cardiac compressorat the controlled interval. This, however, presents difficulty in manyinstances, especially in ambulances where electrical power is minimaland is also erratic due to the large number of powered sirens, flashinglights, normally operated, and to the varying engine speed. To bedependent upon a small extra battery for control power supply is riskydue to battery failure probabilities. Yet, control of the compressor isessential, and should be on a synchronized time basis for optimumeffect. Moreover, control of the compressor should be transferablesmoothly between automatic and manual control means of the poweroperated compressor, for dependability and continuity of treatment atall times, even during patient transfer.

A cardiac compressor, to be effective for ambulance use, must be capableof fitting into the vehicle without substantial space consumption due tothe extremely limited space factor involved. Yet, in spite of itscompactness, the cardiac compressor must be capable of sufiicient powerand stroke to compress even the largest mans chest which might beencountered, about /5 of its thickness.

One disadvantage encountered with known cardiac compressors is the greatdifiiculty of placing the patient between the fixed back supportingplatform and the reciprocable pressure applicator. The compressor unitsare basically C-shaped in configuration, with the lower leg of the Cbeing the rigid platform, and the upper leg containing the reciprocableplunger. Since the unconscious patient has to be moved directly sidewayswith respect to the known compressors, proper positioning of the patientwith respect to the unit often becomes extremely difficult. This isparticularly true with large heavy patients, and time is severelylimited to a matter of seconds. If the patient is otherwise injured, theproblem of sandwiching him between the operative components of thecardiac compressor becomes very crucial.

Once a cardiac compressor is in operative position relative to thepatient, its safe effective operation is achieved only with exactlylocated and properly regulated force application to the patient.Locating the cardiac compressor on the patient is crucial. If it is toohigh on the sternum, it will not compress the heart adequately. If it istoo low, it will damage the liver. Moreover, the pressure on the heatmust be just the proper amount, i.e. sutficient to force the blood fromthe heart, but not too much to damage it. This is achieved with about20% chest thickness compression. The actual amount of chest compressionforce varies widely with chest thickness and strength, thereby causingthe pressure applied to he very important.

In addition to these factors, it has been determined that the cardiaccompressor must be regulatable to not only control the time intervalbetween stroke pulses, but also the rate of pressure application for therate of pressure release with each timed stroke for proper pumpingaction from the heart.

It is one object of this invention to provide a cardiac compressorapparatus that has exactly controlled stroke timing without anydependency upon an electrical supply source. The novel device has anaccurate and variable, regulated timed interval constantly controlledand dependably operated by the same pneumatic supply source that powersthe compressor. The unit is subject to accurate control and operationmerely by attachment of a typical oxygen cylinder supply line in anambulance, for example, or in any other emergency treatment facilites,such as piped oxygen in the hospital.

Another object of this invention is to provide a unique, pneumaticallyoperated cardiac compressor having a special valving system thatachieves accurately controlled, pneumatic actuation of the poweroperation for exact time interval pulsing. It also enables manualover-riding control of the pneumatically powered operation for on timumsafety. The device is attachable to a conventional oxygen supply tank inan ambulance or useable with other compressed gas supply sources as in ahospital. Yet, it uses only a small amount of gas.

Another object of this invention is to provide a pneumaticallycontrolled, pneumatically powered cardiac compressor device employing aspecial valve so that the entire device is easily portable. It can thusbe easily carried from place to place with the patient. The device isalso very compact, thereby being useful on a stretcher as in anambulance, or in a hospital, or any other place, while being portablewith the patient on the stretcher for continuity of treatment. Yet, ithas a power stroke of varying capaciy and timing suitable for persons ofdifferent size and strength, with timing intervals being regulated inaccordance with the pressure to be applied to the persons chest, inspite of its lightweight and compactness.

Another object of this invention is to provide a pneumatically operatedcardiac compressor that is collapsible to a storage conditionin a smallspace, but is capable of remounting for use in seconds.

Another object of this invention is to provide a cardiac compressorhaving separable components enabling convenient positioning of its rigidsupport under the patient while separated from the compressor plunger.It has capacity for snap-action assembly in a few seconds time forimmediate usage, to enable emergency treatment to be given within lessthan /2 minute. Even large, heavy persons can be positioned with theplunger over the chest and the rigid support under their back with aminimum of effort, and without trying to push or drag the patientbetween these components. It can even be positioned, assembled andoperated from a narrow stretcher, vehicle seat, bed or couch.

*Another object of this invention is to provide a cardiac compressorassembly having specially controlled rate of pressure application duringcardiac compression (systole) and rate of pressure release duringcardiac refilling (diastole) to achieve optium pumping action formaintaining life.

Another object of this invention is to provide a cardiac compressor thatclearly indicates the amount of chest defiection with each stroke,thereby enabling immediate accurate adjustment to the necessary amount.

These and several other objects of this invention will become apparentupon studying the following specification in conjunction with thedrawings in which:

FIG. 1 is a perspective view showing the novel device in a position ofuse on a patient;

FIG. 2 is a perspective view of the opposite side of the device fromthat side illustrated in FIG. 1;

FIG. 3 is a sectional view taken on plane IIIIII of FIG. 2, showing thecompressor plunger;

FIG. 4 is an enlarged, plan fragmentary view of the adjustableconnection between the compressor arm and support post in the apparatusof FIGS. 1 and 2;

FIG. 5 is a perspective, fragmentary, exploded view of the releaseableconnection between the mounting plate of the support post and connectorplate of the platform of the apparatus of FIGS. 1 and 2;

FIG. 6 is a side elevational sectional view of the apparatus in FIG. 5;

FIG. 7 is a perspective enlarged view of the pneumatically operated timecontrol valve;

FIG. 8 is a bottom fragmentary view of the base of the unit showing thecontrol system in place;

FIG. 9 is a schematic diagram of the pneumatic control and operationalsystem; and

FIG. 10 is a graphical representation of a typical time versus pressurecurve resulting from the novel control system of the apparatus.

Referring now specifically to the drawings, the cardiac compressorassembly 10 includes the base platform subassembly 11, the supportpillar or post 14 extending upwardly from one edge of the rigid platform12 of subassembly 11, compressor arm 16 extending out over the baseplate or platform, and plunger subassembly 18 mounted to the other endof arm 16 over the platform.

The base plate or platform 12 is of rigid metal construction, normallyof aluminum. It has a generally fiat upper surface to receive the backof a patient. It provides a rigid, non-flexing support when the patientschest is compressed. It tapers from its thinner outer end to theopposite thicker end 20 of enlarged height. This latter end has a hollowunderside to receive the pneumatic control system 22 mounted to theunderside of the unit (FIG. 8), and communicating to the compressorthrough port connections to be described.

Aflixed to the upper surface of this enlarged end portion 20 of platform12 is a rigid mounting plate 26 having one end extending out over theedge of the platform. This mounting and port connector plate (FIG. 5)has an air line inlet fitting 30 mounted thereon and communicating witha passageway from the fitting to control assembly 22 in a manner to bedescribed. It also has a port 32 extending through the plate andsurrounded by an O-ring 34 received in a groove to form a positive sealwith the under surface of the column base plate 36 when Pressedtogether. Port 32 communicates with a port 38 communicant with theinside of the hollow enclosed column or post 14. This post acts as areservoir for the gas, in a manner to be described hereinafter.

Another port 40 in plate 26 is surrounded by a sealing O-ring 42 adaptedto contact and seal against the under surface of column plate 36, andcommunicating with port 46, to flexible hose 48 that extends to plungersubassembly 18 (FIGS. land 2).

Another opening 50 extends through plate 26 at the outer end of theplate. This orifice is intersected transversely by a blade latch 54having a handle 56 on one end and a pivot mount 58 to plate 26 on theother end. This blade latch fits within a slot 60 in the outer extendingend of plate 26. It is normally retained by spring 62 in a position tointersect the diameter of the through opening 50, as illustrated in FIG.6.

The base 36 of support column 14 releasably interfits with mountingplate 26 by having its inner edge 36' slidablyreceived beneath theoverlying flange 66. This flange is part of a support block that isaffixed to plate 26 along its inner edge. It extends upwardly and outover the edge of plate 36. Alignment of plate 36 with plate 26 isfacilitated adjacent flange 66 by a pair of straddling alignment pins65. Attached to the opposite end of column base plate 36 is a taperedcatch 70 having a narrow neck portion 72 between the enlarged headthereof and plate 36, into which latch blade 54 is biased to retain theassembly in tightly fitting condition once it is assembled. This catchis mounted to plate 36 by a suitable stud and nut 74 connection. Thesupport cylinder can be readily connected or disconnected, with the gasline connections being automatically completed with latching of theunit. Operational forces will not be applied to the latch, but only tothe retention flange 66 which is rigid and securely attached.

Secured to support column 14 is the compression arm 16, which extendsradially therefrom. This compression arm includes a peripheral collarthat surrounds the column 14. This collar is rotatable on the post 14and is vertically slidable when locking means 82 is loosened.

This locking means includes a pair of generally cylindrical.

abutting elements 84 and 86 on threaded stud 88. A knurled knob 90 isattached to one end of this stud for manual loosening and tightening.Elements 84 and 86 have tapered faces 92 and 94 respectively, adjacentto and abutting the periphery of post 14 to bind the assembly. Thepassage in element 86 is unthreaded and forms a slip fit with stud 88.Passage in element 84 is threaded to receive threaded stud 88. To bindthe assembly, knob is rotated so that collar 91 presses element 86toward post 14 while threaded stud 88 simultaneously draws element 84toward the opposite side of post 14 to bind on it. Once this bindingconnection is made, compression arm 16 is fixed vertically androtationally with respect to the support column. This adjustment featureis important for reasons to be described hereinafter.

Mounted to the outerradial end of compression arm 16 is plungersubassembly 18. This includes a basic cylinder housing (FIG. 3). havinga gas line fitting connection 102, into which fitting 104 from hose 48interfits, to supply the upper end of the cylinder with compressed gas.The lower portion of the cylinder includes a cylindrical bushing 108.The bushing is integrally attached to an annular plate 114 abutting thebottom face of cylinder 100 (FIG. 3). This plate as well as theretaining cup 110 and a lubricating wiper 116 are secured to the bottomannular face of cylinder 100 by suitable screws 112.

The plunger element 120 is preferably basically hollow in configuration,having an enclosing upper end cap 122 inside cylinder 100. This end caphas a peripheral edge which extends out beyond plunger 120 to abut withthe upper edge of bushing 108 and limit the downward stroke of theassembly. The lower end of plunger 120 includes a chest contactingresilient pad 128 which is adapted to abut the lower portion of thepatients sternum in a manner to be described hereinafter.

Inscribed around and into the periphery of plunger 120 are spaced rings121 of small indicia marks arranged in annuli. These are clearly visibleto the operator as the plunger reciprocates vertically. The smallvertical dimension of the small marks prevents the mark from beingentirely concealed inside the cylinder when the plunger stops at theparticular mark ring. The alignment of any one mark with the bottom faceof cylinder 160 is indicative of piston extension and, therefore, of thedepth of compression of the patients chest. Normally, these markings areplaced approximately at one-half inch intervals, so that heavier rings121' and 121" are at intervals of one and one-half inches. This is thenormal deflection required for the average adult chest. The strokelength of the plunger can be regulated accurately by watching theseindicia as the regulatory valve knob 140 (FIG. 2) is rotated and duringoperation, as explained more specifically hereinafter.

Assembly 22 (FIGS. 8 and 9) allows pneumatic control of thepneumatically powered operation of the cardiac compressor. This systemis supplied by pressurized gas, for example from the pressurized oxygentank (not shown) in a conventional ambulance. It is supplied through ahose 144 (FIG. 1) that connects to the releasable coupling 30. Thepnuematic supply and control system that supplies gas supply hose 144communicates through ports 32 and 38 (FIG. to reservoir 14 inside column14- through branch line 144 (FIGS. 6 and 9), and then separates intopressure lines 152 and 169. Line 152 includes manually adjustableactuating pressure regulator 154 operated by knob 140 (FIG. 2). Thisline 152 communicates with the basic control valve 150 through an inletport 156. The second branch conduit 160 from the supply linecommunicates through a control pressure regulator 162 and through acontrolled constriction 164 such as an orifice plate, through branchedconduit 169, to inlet port 168 of valve 150, and also to inlet port 170of the automatic on-off pneumatic switch 172. This pneumatic switchincludes a valve spool 174 inside housing 176, operable by extendingsuitable manual knob 178 which may have a push-pnll rigid connection(FIG. 9) or a toggle connection like that shown at 178 mounted tohousing base 20 in FIG. 2.

Control valve 150 includes a basic housing construction 180 having avalve spool 182 inside the valve body. Magnetically responsive pistons134 and 186 are attached to opposite ends of the spool and are locatedin piston chambers 188 and 190, respectively.

These piston chambers are closed by suitable end cap assemblies 192 and194 illustrated graphically in FIG. 9 and structurally in FIG. 7. Theportion of chamber 190 adjacent the inner face of piston 186communicates through a port 200 and a conduit 202 to a small gasreservori chamber 204 which may be simply a hollow cylindrical vessel,for example. This reservoir also communicates through conduit 206 toanother port 208 in valve body 180. Both of these ports areinterconnected pneumatically through an annular recess passage 212around spool 182 when the spool is at the far right position illustratedin FIG. 9. At the left position of the spool (relative to the drawing)port 168 is communicant with passage 216 in the valve spool body, whichis in communica- 6 tion through conduit 218 to a second reservoirchamber 220. This reservoir chamber also communicates through anotherconduit 222 back to spool 174 of manual switch 172, and specificallywith annular recess 226 therearound.

In one position of this spool 174, it therefore is in operativecommunication with conduit 230 that communicates with the side ofchamber adjacent the outer face of piston 186. In the other position ofspool 174, conduit 230 is in operative communication with conduit 169which communicates with port 168 in the valve body 180.

Spool 132 also includes an annular recess 236 intermediate its ends,communicating with an exhaust outlet port 238 in the valve body, andalso with a branch passage 216 interconnecting with passage 216. Inanother position, recess 236 interconnects exhaust port 238 to passage208' branched from passage 208 in the valve body.

A third annular recess 244 in valve spool 182 is communicable in itsfirst position to the right (FIG. 9) with port 248 and output pressureconduit 246, and also exhaust port 250 to allow flow therebetween. Inits second position to the left, it interconnects port 156 of conduit152 with outlet port 248 to conduit 246. This outlet conduit 246interconnects with ports 40 and 46 (FIG. 5) to supply pressurized gas ona controlled basis to hose 48 to the top end of the plunger cylinder.

As noted previously, pistons 184 and 186 are magnetically responsive.Mounted adjacent the pistons is a pair of magnets 260 and 268 for therespective pistons 184 and 186. By positioning these magnets at acontrolled distance with respect to the outer faces of the pistons, thebias necessary to overcome the magnetic attraction of each piston to itsown magnet and shift the spool in the opposite direction, is controlled.This enables adjustment of the pressure necessary to build up in thealternate reservoir capacitor chambers 204 and 220 to shift the valvespool in one direction or the other. This controls the time interval ofvalve shifting, as will be described more specifically hereinafter.Mounting of the magnets to the end of valve 150 can be by extending endcaps 192 and 194 to surround the magnets and overlap the ends thereof.Spacing of the magnets to the pistons can be achieved by suitablespacers 193 and/or by threadably engaging the outer attached sleeve 195around the magnet (e.g. magnet 260) with the surrounding end capretainer 192 such as at 192. Preferably, this timing adjustment isdetermined and fixed at the factory, to have a particular controlledtime relationship to the pressure applied.

A fixed rod extension 270 is attached to piston 184 and extends throughone magnet 260 out of the housing to terminate in a manual knob 272.This manual knob (FIG. 9) extends from the end of base 20 (FIG. 2) to bemanually operable for actuating the valve manually.

Operation Because of the compactness of the novel device, and itsrelatively lightweight and small size, it can be readily adapted for usein ambulances, on the back seat of a police car, in hospitals, atbusiness establishments or manufacturing facilities for industrialsafety purposes, in the home, or in a variety of other places.

The device, due to its particular features, is convenient to use. It maybe placed by one person in the proper operative position with respect tothe patient.

Assuming for example, that the patient P (FIG. 1) requires cardiaccompressive treatment on an emergency basis, he is placed into theoperative relation illustrated in FIG. 1 when the device isdisassembled. That is, to detach the upper end of the unit, column 14 ofthe unit is grasped, and knob 56 is pulled to release the latch whenblade 54 is removed to the phantom position illustrated in FIG. 5against the bias of spring 62. This enables the column to be tiltedforwardly to the position illustrated in FIG. 5 and FIG. 6, so that edge36' of plate 36 can he slid backwardly, out from beneath hold downflange 66. The column, compressive arm, and plunger are then laid asidefor a moment while the base platform is inserted under the patient. Thepatient is first tilted by grasping his shoulder and rolling him partway onto his side, so that base platform 12 can be slide beneath hisback. He is then rolled back to be flat on the platform. The column isreplaced by inserting edge 36 again under flange 66, tilting the columnvertically up to upright position so that knob 70 is inserted in opening50 to catch beneath blade 54. This not only latches the assemblytogether, but also seals the passage connections at the portsillustrated in FIG. due to the pressure of the O-rings against theunderside of plate 36.

The plunger pad 128 is adjusted relative to the patient to lie over thelower part of his breastbone, i.e. sternum. The exact position isachieved by loosening knob 90 and rotating arm 16 to assume its properlocation. This is important for reasons stated previously.

Simultaneously, while arm 16 is still movable on col+ umn 14, the arm isslid down until pad 128 contacts the chest when the pad and plunger arein the raised position (FIG. 1).

Then, gas supply hose 144, as from a conventional oxygen tank, is thenconnected by coupling 30 to the system, to supply pressurized gas. Thisis done when knob 140 (FIG. 2) is in closed position to preventpremature presusne flow. No pressure then registers on gauge 141. Thepressurized gas, when applied, wil lact as (l) the actuating means forthe plunger, and (2) to operate the timing controller for the plunger.Plunger 120 is initially not pressurized, therefore, and can be held upin its upper, retracted position illustrated in FIG. 1. Normally, itsweight allows it to slide to its lowered position (FIG. 2), but it canbe easily pushed up.

Air flow through line 144 (FIG. 9) will build up in reservoir chamber14- column 14 to act as a buffer and provide a constant, fairly steadypressure supply, even though the oxygen is supplied through a small hosefrom its nk.-

This air supply is allowed to pass from reservoir 14 with controlledopening of regulator 154 \by turning knob 149. This air will applyoperating pressure, controlled by regulator 154 through knob 140 (FIG.2) through conduit 152 and restriction 157 to port 156 in the valvebody. When the spool of the valve assembly 156 is in the position to theright as illustrated in FIG. 9, conduit line 246 (which suppliespressurized gas to hose 4S and to the top of the compressor cylinder) isopen to exhaust port 256 to the atmosphere.

The gas flowing through conduit 160 and regulator 162, which ispreviously adjusted for a particular time interval, fiows throughconstriction 164 to manual switch 172, and to port 168 of the controlvalve. Switch 172 may be placed in the position illustrated in FIG. 9for its automatic cycling control, and will be placed in its secondposition to cause communication between conduits 230 and 169 if valve150 is to be operated manually.

' Assuming that it is to be operated automatically, and that it is inthe position illustrated in FIG. 9, gas passing through conduit 169,port 168, recess 212 in valve spool 132, port 298, conduit 206 toreservoir chamber 204, causes a steadily increasing pressure in chamber204. Pressure increase is gradual due to restriction 164. At the sametime, chamber 220 is exhausted to atmosphere by flow through conduits218 and 216, recess 236 and port 238. As soon as the pressure in chamber204 reaches a predetermined amount to apply a sufiicient pressure topiston 186 to overcome the magnetic attraction between magnet 260 andpiston 184, it will shift piston 186 to the left from that illustratedin FIG. 9, toward magnet 262. When it does this, conduit 152, port 156and recess 244 will allow fiow of pressurized actuating gas from conduit152, through cavity 244 and spool 182, through port 248 and conduit 246,and thence, through ports 40 and 46 (FIG. 5) to hose 43, and thus to theupper end of the compressor cylinder. This exerts downward pressure onthe plunger cap 122 (FIG. 3) to force the plunger downwardly. By turningand thereby controlling pressure knob (FIG. 2) to regulator 154 (FIG.9), the amount that the plunger is forced down against the breastbone tocompress the chest and squeeze the heart is determined. This will varywith the particular size and physical condition of the patient.

If a man having a thick rigid chest is to be the patient, the amount ofpressure needed will be greater to compress his chest 20% of itsthickness, than if a smaller person of more fragile nature is treated.If, for example, a small baby is being treated, the amount of presusrewill be very small to bend his breastbone and compress the heart, due tothe relatively small amount of plunger movement needed, and to therelative flexibility of his breastbone. By watching indicia 121 on theplunger (FIG. 3), the movement can be accurately seen.

The actual time of piston extension, i.e. the interval between the downstroke and its release for retraction is determined by filling of thesecond reservoir chamber 220 (FIG. 9).

As soon as valve spool 182 is shifted to the second position from thatillustrated in FIG. 9, gas passes from conduit 169, through port 168,recess 212, port 216, conduit 218, to fill reservoir chamber 220.Pressure in chamber 220 is also exerted on the outer face of piston 186,due to the connection through conduits 222 and 236 through the selectorswitch valve 172. Therefore, as soon as the pressure in this chamber hasbuilt up sufiiciently to overcome the magnetic attraction of magnet 262to piston 186, the valve shifts back to the opposite direction.Meanwhile, pressure in chamber 204 will be bled to atmosphere throughconduits 2G6 and 208', recess 236 and port 238. Once valve is back inits initial position, the time interval for shifting it again foranother compressive movement is the same as that already described.

When the valve shifts back to its initial position, pressurized airexerted on plunger 120 is released by communication of conduit 246 toexhaust port 250 (FIG. 9) through annular concavity 244. This release ofpressure on the plunger, and thus on the breastbone allows the naturalresilience of the chest to expand it, thereby allowing the heart toexpand and refill with blood (diastole). The valve spool repeatedlyreciprocates back and forth at these time intervals which are preset independence upon the location of magnets 260 and 262, the opening of restrictor 164, and the volume of chambers 204 and 220. After each shift,one pressure chamber begins building up in pressure while the other isexhausted to atmosphere.

Often it is desirable to have spool 182 of valve 150 remain at one endof the valve body for a longer time interval than at the other end. Thisenables time control of both the non-compression interval andcompression interval, to allow optimum operation. 7

Exhaust port 12 is purposely quite large to cause an almost immediateexhaust of fluid pressure from the plunger. On the other hand, theapplication of actuating pressure through conduit 152 and port 156,hence, down through cavity 244, port 248, conduit 246, and thencethrough hose 48 to the top of the compressor cylinder is on a regulated,gradual basis. The plunger does not shift all at once, therefore, withapplied pressure.

It is advisable medically to depress the breastbone and heart on acontrolled gradual basis of a particular nature, rather than having animmediate thrust. An instant thrust may damage the heart and otheranatomy and does not produce optimum pumping action. It has been foundwith extensive experimentation that a pressure application curve of thetype illustrated in FIG. 10 is that which should be followed.Consequently, a restrictor or restriction valve 157 is located (FIG. 9)in conduit 152 to regulate the rate of gaseous flow to the plunger.

Since the pressure build up on the plunger is exponential, the mostconvenient manner of expressing the rate of pressure build up is by atime constant. It has been determined that the time constant forpressure build up on the plunger, for most effective pumping action fromthe heart, and for safety to the heart, should be at least 0.15 secondto increase pressure to within (1/e)th of the total constant pressure tobe applied wherein e is the Napierian logarithm base. The restrictorvalve 157 allows throttling of gas inlet to achieve this time constant.The time constant can be somewhat greater than this also.

Pressure release from the unit is also of course exponential in nature,but by providing a substantially large exhaust outlet 25%, release isvery rapid. It has been found to be desirable to have release as closeto instantaneous as possible, for best heart refill action. This allowsthe rib cage to spring back rapidly. A time constant of about 0.05second for pressure drop to within (1/e)th of the total pressure drop issatisfactory. If possible, even a smaller time constant should beobtained.

If for some reason it is necessary to operate the control valve 159manually, switch valve 172 is shifted manually by pushing spool 174 tothe left position, so that conduit 236 communicates with conduit 169.Byso doing, pressurized gas from conduit 169 flows directly through line230 to piston chamber 1%). Chamber 188 is either open to atmospheric(with spool at extreme left position) or filled at control pressure(with spool at right position). In the first position, full differentialpressure will be exerted on piston-armature 186 to move the spool to theextreme right position, at which time an equal pressure will develop onthe opposite side of the piston. Due, however, to a differential area onopposite sides of the piston (produced by the inside face being coveredby the end of the spool) there still remains a small net differentialforce to assure full return of the armature to the extreme rightposition, where it is held rimarily by the differential magneticcoercive force. In this position, the total holding force is much lessthan if full differential control pressure were applied to the piston.Thus, the manual knob 272 may be easily depressed to supply outputpressure to the plunger. Upon releasing knob 272, the ditferentialpressure built up after the preset delay time will return the spool tothe extreme right (exhaust position). It will stay there until themanual knob is depressed again. Thus, by depressing manual knob 272 ofvalve 156 repeatedly, the compressor will intermittently compress thepatients breastbone and heart in a similar fashion to that automaticallydone previously.

As mentioned previously, the amount of chest deflection is preferably20% of the patients chest thickness. Since the amount of pressurenecessary to depress different patients chests 20% varies greatly, e.g.from about 60 p.s.i. to about 80 p.s.i., the control knob 14% will beadjusted slowly from pressure up to the desired amount. This isdetermined easily by Watching the amount of extension of plunger 120with each stroke. This is clearly indicated from the relationship ofindicia 121 with respect to the bottom of cylinder 1&0.

It will be apparent after studying this disclosure that the uniquedevice is an extremely desirable emergency unit that is useable in anyof a variety of locations and situations. Indeed, actual use of thedevice presently in emergency efforts have proven this to be true. It isnot only lightweight and compact, it is convenient to use, even on avehicle seat or on a stretcher, is easily inserted beneath the patient,and is readily operated by a person with only a small amount oftraining. Furthermore, its controlled time operation is dependable, aswell as variable and controllable. It is completely independent of anyelectrical control systems, being controlled, as Well as operated, fromthe same pneumatic supply attached to it, and available in anyambulance, hospital, or other emergency facility.

The complete assembly can be manufactured and sold relativelyinexpensively, to serve as an important emergency adjunct to equipmentnow available.

Several additional advantages will probably occur to those in the artupon studying the foregoing description of the preferred device. Also,it is conceivable that certain minor details of structure could bechanged Within the concept presented, without departing from theinvention as taught. Therefore, the invention is to be limited only bythe scope of the appended claims and the reasonably equivalentstructures to those defined therein.

I claim:

1. A cardiac compressor comprising a base having a support platform; asupport column rigidly attached to said base at the bottom portionthereof and extending upwardly therefrom at an end of said supportplatform; a compressor arm rigidly attached to an upper portion of saidsupport column and extending laterally therefrom; and a verticallyreciprocatable compressor rigidly attached to said arm; said arm andcompressor constituting a subassembly removable as a unit from saidbase; said column having an attachment element and an engagableprojection on its lower end; said base having a receiving and retentionmeans for said attachment element, said receiving and retention meanscomprising a flange engagable with said attachment element near saidplatform and including releasable latch means spaced from said flangeand aligned with said engagable projection enabling separation of saidcolumn arm and compressor from said base, for insertion of said platformunder a patient, and rapid reassembly thereof for cardiac compressionwith regard to the patient.

2. A cardiac compressor comprising; a base having a support platform; asupport column rigidly attached to said base at the bottom portionthereof and extending upwardly therefrom at an end of said supportplatform; a compressor arm rigidly attached to an upper portion of saidsupport column and extending laterally therefrom; and a verticallyreciprocatable compressor rigidly attached to said arm; said column,arm, and compressor constituting one assembly removable as a unit fromsaid base; said column having an attachment plate on its lower endextending substantially perpendicular to said column; said base having agenerally horizontal surface to engage said plate; a plate retentionflange projecting up from the end of said surface closest said platform,and extending out over said surface, said flange being so shaped as tointerfit one end of said plate nearest said platform when said plate ispositioned therebeneath; and releasable latch means between said baseand the opposite end of said plate to retain said column upright andretain said one plate end under said flange during cardiac compression.

3. A cardiac compressor comprising: a base including a support platformfor a patients back; a support column extending vertically from one endof said base; a compressor arm mounted to said column, extendingradially therefrom and terminating in a fluid cylinder over saidplatform; a piston plunger reciprocatable in said cylinder toward andaway from said platform; said column having a mounting plate on itsbottom end; said base including plate receiving and retention means toretain one end of said mounting place; and means on said base torestrain another end of said plate whereby said plate is rigidlyattached to said base, and rotational movement of said column isprevented.

4. The compressor in claim 2 wherein said latch means includes anopening in said base, a slotted vertically adjustable projectionextending down from said plate to be received by said opening; and alatch blade pivotally attached near one end to said base, and movableand biased transversely of said projection into its slot to retain saidassembly until released.

5. A cardiac compressor comprising: a base forming a patients backsupporting platform; one end of said base being hollow; a support columnextending vertically up from said one end; a compressor arm extendingradially out from said column and terminating in a fluid cylinder; apiston plunger in said cylinder, reciprocable toward and away from saidplatform and having a sternum contact pad on its lower end; a mountingplate on the bottom of said column; plate receiving and retention meanson said one end of said base; releasable latch means between said plateand said retention means; said column being hollow and comprising a gasstorage and bufler chamber; a main gas line connection to said base;pneumatic pulse timing valving control means mounted in said hollowbase; gas conduit passageway means between said gas line connection,said chamber, said control means and said cylinder including coincidentports in said base and said plate; and said ports including compressionseals between said base and plate, automatically sealing around saidports with connection of said plate to said receiving and retentionmeans.

6. A cardiac compressor comprising: a base forming a back supportingplatform; a support column extending vertically up from one end of saidbase; a compressor arm extending radially from said column above saidplatform, and terminating in a fluid cylinder; a piston plunger in saidcylinder, reciprocable toward and away from said platform and having acontact pad on its lower end; a mounting plate on the bottom of saidcolumn; plate receiving and retention means on said one end of saidbase; releasable latch means between said plate and said retentionmeans; said column being hollow and comprising a gas storage and bufferchamber; a main gas line connection to said base; passageway meansbetween said gas line connection, said chamber, and said cylinder,including connecting ports between said base and said plate; and saidports including compression seals automatically engaged with connectionof said plate to said receiving and retention means.

7. A pneumatic operated, pneumatically controlled cardiac compressor,comprising: a base including a back supporting platform; means tosupport a cylinder above said platform; piston plunger means in saidcylinder, reciprocable toward said platform under pressure, andreleasable to be pushed away from said platform by a patients rib cageexpansion; a pneumatically operated timing control valve; gas supplymeans to said valve; controlled gas conduit means through said valve tosaid cylinder; said valve including a valve element shiftable between afirst position allowing gaseous flow from said supply connection meansto said cylinder, to a second position allowing exhaust from saidcylinder to the atmosphere; piston means contained in a piston chamberand connected to said element, being responsive to gaseous pressure fromsaid supply to shift said element between said positions; gas passagemeans from said supply connection means through said valve to either endof said chamber, the reciprocation of said valve causing alternate flowto either end of said chamber in its alternate positions with shiftingthereof; and pressure build up regulating means in said gas passagemeans allowing time control of pressure build up suflicient to shiftsaid piston means and valve element.

8. A pneumatically operated, pneumatically controlled cardiaccompressor, comprising: a base including a back supporting platform;means to support a cylinder above said platform; piston plunger means insaid cylinder, reciprocable toward said platform under pressure, andreleasable from the pressure to be pushed away from said platform by apatients rib cage expansion; a pneumatically operated timing controlvalve; gas supply connection means to said valve; controlled gas conduitmeans from said valve to said cylinder; said valve including a valvingelement shiftable between a first position allowing gaseous flow fromsaid supply connection means to said cylinder, to a second positionallowing exhaust from said cylinder to the atmosphere; a pair of pistonscontained in piston chambers and connected to said element in oppositionto each other, at least one of said pistons being responsive to gaseouspressure from said supply to shift said element between said positions;said piston means being magnetically responsive; magnetic attractionmeans adjacent the pistons, alternately biasing them and said valveelement in each of the shifted positions, to obtain. a snap action ofsaid element upon the occurrence of a pressure increase on one of thepistons greater than the biasing force caused by the magneticattraction; gas passage means from said supply connection means throughsaid valve to either end of said chamber containing said one piston, thereciprocation of said valve causing alternate flow to either end of saidchamber with shifting thereof; and pressure build up regulating means insaid passage means allowing time control of pressure build up sufficientto shift said piston means and valve element, thereby allowing controlof pressure pulse applications and releases.

9. The apparatus in claim 8 including means for adjust ing the magneticattraction of said magnetic attraction means for said pistons to varythe time of pause of said valve element at each position.

10. A pneumatically operated, pneumatically controlled cardiaccompressor, comprising: a base including a back supporting platform;means to support a cylinder above said platform; piston plunger means insaid cylinder, reciprocable toward said platform under pressure, andreleasable to be pushed away from said platform by a patients rib cageexpansion; a pneumatically operated timing control valve; gas supplyconnection means to said valve; controlled gas conduit means from saidvalve to said cylinder; and said valve including a valving elementshiftable between a first position allowing gaseous flow from saidsupply connection means to said cylinder, to a second position allowingexhaust from said cylinder to the atmosphere; piston means contained inpiston chambers and connected to said element, at least one of saidpistons being responsive. to gaseous pressure from said supply to shiftsaid element between said positions; gas passage means from said supplyconnection means through said valve to either side of said cylindercontaining said one piston, the reciprocation of said valve causingalternate flow to either end of said chamber with shifting thereof;pressure build up regulating means in said gas passage means allowingtime control of pressure build up suflicient to shift said piston meansand valve element; said controlled gas conduit means includingrestriction control means to increase the time constant of pressureincrease in said cylinder to at least about 0.15 second for build up towithin (l/e)th of stable pressure wherein e is the Napierian logarithmbase; and said valve including exhaust means to the atmosphere allowingcylinder pressure exhaust with a time constant of at least about 0.015second for pressure decrease to within (1/e)th of atmospheric pressure.

11. A cardiac compressor, comprising: a base having a support platform;a cylinder; a plunger reciprocable in said cylinder toward said platformunder fluid pressure; said plunger capable of extending down from saidcylinder and having a resilient contact pad on its lower end; means torigidly attach said cylinder to said base such that said plunger isvertically reciprocatable and indicator markings at vertical intervalson said plunger, enabling its degree of extension from said cylinder tobe readily seen as it reciprocates, thereby enabling the compressoroperator to accurately visually determine the depth of chestcompression.

12. A cardiac compressor, comprising: a base having a support platform;a support column mounted vertically upright on one end of said base; acompressor arm extending radially from said column and having a cylinderat the outer end; a plunger reciprocable in said cylinder toward saidplatform; pneumatic time pulse control valve means to extend saidplunger repeatedly toward said platform and including valve operatinginlet port means and inlet port means for cylinder actuating gas; gaspassage 13 means from said pneumatic time pulse control means to saidcylinder; and gas supply connector means and branched conduit meanscommunicant with both said inlet port means to supply both from the samesupply each of said branches containing a pressure regulator.

13. A pneumatically operated, pneumatically controlled cardiaccompressor, comprising: a base including a back supporting platform;means to support a cylinder above said platform; piston plunger means insaid cylinder, reciprocable toward said platform under pressure, andreleasable to be pushed away from said platform 'by a patients rib cageexpansion; a pnuematically operated timing control valve; gas supplymeans to said valve; controlled gas conduit means through said valve tosaid cylinder; said valve including a valve element shiftable between afirst position allowing gaseous flow from said supply connection meansto said cylinder, to a second position allowing exhaust from saidcylinder to the atmosphere; piston means contained in a piston chamberand connected to said element, being responsive to gaseous pressure fromsaid supply to shift said element between said positions; gas passagemeans from said supply connection means through said valve to either endof said piston chamber, the reciprocation of said valve causingalternate How to either side of said chamber in its alternate positionswith shifting thereof; and pressure build up regulating means in saidgas passage means allowing time control of pressure build up suflicientto shift said piston means and valve element; and manually shiftable,pneumatic valve switch means in said gas passage means and in said gassupply means, shiftable between a first position allowing the aspressure to operate said valve element in both directions, and a secondposition allowing manual operation of said valve element.

14. The apparatus in claim 13 wherein said valve switch in said secondposition allows reduced pressure actuation of said valve element in onedirection and prevents pressure actuation of said valve element in theopposite direction to require manual shifting thereof.

15. A cardiac compressor apparatus, comprising: a base, and supportmeans for supporting a reciprocable compressor over said base, and areciprocable compressor on said support means; timing control meanscausing timed pulses of said compressor toward said base to applypressure intermittently to the sternum and heart of a patient on saidbase; and pressure increase rate control means to said compressormaintaining the time constant for pressure increase on said compressorand thus by said compressor to a patient on said base to be at leastabout 015 second to develop pressure to within (1/e)th of the normalmaximum operating pressure wherein e is the Napierian logarithm base.

16. A cardiac compressor apparatus, comprising: a base, and supportmeans for supporting a reciprocable compressor over said base, and areciprocable compressor thereon; timing control means causing timedpulses of said compressor toward said base to apply pressure to apatient on said base; and pressure increase rate control means for saidcompressor maintaining the time constant for pressure increase of saidcompressor to a patient on said base to at least 0.15 second to developpressure to within (l/e)th of the normal maximum operating pressurewherein e is the Napierian logarithm base, and pressure decrease meansallowing practically instantaneous release of pressure of saidcompressor.

17. The apparatus in claim 16 wherein said compressor includes a fluidpressure cylinder and a piston plunger therein, said increase ratecontrol means is a gaseous flow restrictor, and said decrease means isan unrestricted gaseous exhaust port means.

13. A cardiac compressor, comprising: a base, forming a back supportingplatform; one end of said base being hollow; a support column extendingvertically up from said one end; a compressor arm extending radiallyfrom said column and terminating in a fluid cylinder; a piston plungerin said cylinder, reciprocable toward and away from said platform andhaving a sternum contact pad on its lower end; said supporting columnbeing cylindrical; said arm having a collar around said column;releasable binding means in said collar against said column to allowvertical and radial adjustment of said arm when loosened; said bindingmeans including a threaded stud with a pair of surrounding bindingelements thereon, having facing tapered ends contacting an arcuateportion of said cylinder adjacent to and opposite each other; and a knobon said stud allowing said elements to be forced together against saidcylinder and lock said collar and arm thereon.

19. A cardiac compressor, comprising: a base having a support platform;a support column; a compressor arm; and a reciprocable compressor onsaid arm including a fluid cylinder and a reciprocable piston plunger insaid cylinder, with a sternum contact pad on its lower end; saidsupporting column being cylindrical; said arm having a collar aroundsaid column; releasable binding means in said collar against said columnto allow vertical and radial adjustment of said arm when loosened withrespect to a patient on said paltform; said binding means including athreaded stud with a pair of surrounding binding elements thereon,having facing tapered ends contacting an arcuate portion of saidcylinder adjacent to and opposite each other; and a knob on said studallowing said elements to be forced together against said cylinder andlock sail collar and arm thereon; indicator markings at verticalintervals on said plunger, enabling its degree of extension from saidcylinder to be readily seen as it reciprocates, thereby enabling thecompressor operator to accurately visually determine depth of chestcompression; said column, arm and compressor constituting one assemblyremovable as a unit from said base; said column having an attachmentplate on its lower end; said base having one hollow end and havingthereabove a surface to engage said plate; a plate retention flangeprojecting up from the end of said surface closest said platform, andextending out over said surface, under which one end of said platenearest said platform can be slid; releasable latch means between saidbase and the opposite end of said plate, to retain said column uprightand retain said one plate end under said flange during cardiaccompression; said latch means includes an opening in said base, aslotted projection extending down from said plate to be received by saidopening, and a latch blade pivotally attached near one end to said base,and movable and biased traversely of said projection into its slot toretain said assembly until released; said column being hollow andcomprising a gas storage and buffer chamber; a pneumatically operatedtiming control valve in said hollow base end; gas supply connectionmeans to said valve; gas conduit passageway means between said gassupply line connection, said chamber, and said control valve, includingcoincident ports in said base and said plate; said ports includingcompression seals between said base and plate, automatically sealingaround said ports with connection of said plate to said base; said valveincluding a valving element shiftable between a first position allowinggaseous flow from said supply line connection to said cylinder, and asecond position allowing exhaust from said cylinder to the atmosphere; apair of pistons contained in pressure chambers and connected to saidvalving element in opposition to each other, being responsive to gaseouspressure from said supply line connection to shift said element betweensaid positions; said piston means being magnetically responsive;magnetic attraction means adjacent the pistons, alternately biasing themand said valving element in each of the shifted positions, to obtain asnap action of said element upon the occurence of a pressure increase onone of the pistons greater than the biasing force caused by the magneticattraction; means for adjusting the magnetic attraction of said magneticattraction means for said pistons to vary the time of pause of saidvalve element at each position;

15 gas passage means from said supply connection means through saidvalve to said chambers; said valve causing alternate flow to saidchambers with shifting thereof; pressure build up regulating means insaid gas passage means allowing time control of pressure build upsuflicient to shift said piston means and valve element, therebyallowing control of pressure pulse applications and releases; said gasconduit passageway means including restriction control means to increasethe time constant of pressure increase in said cylinder to at leastabout 0.15 second pressure to develop to within (1/e)th of stablepressure wherein e is the Napierian logarithm base; and said valveincluding exhaust means to the atmosphere allowing cylinder pressureexhaust with a time constant of at least about 0.05 second to decreasepressure to within (1/e)th of atmospheric pressure; and manuallyshiftable, to pneumatic valve switch means in said gas conduitpassageway means and said gas passage means, shiftable between a firstposition allowing the gas pressure to operate said valve element in bothdirections, and a second position allowing manual operation of saidvalve element; said valve switch in said second position allowingreduced pressure actuation of said valve element in one direction andpreventing pressure actuation of said valve element in the oppositedirection to require manual shifting thereof.

20. A pneumatically operated, pneumatically controlled system,comprising: fluid responsive means; a pneumatically operated timingcontrol valve; gas supply means to said valve; controlled gas conduitmeans through said valve to said fluid responsive means; said valveincluding a valve element shiftable between a first position allowinggaseous flow from said supply connection means to said responsive means,to a second position allowing exhaust from said fluid responsive meansto the atmosphere; piston means contained in a piston chamber andconnected to said element, being responsive to gaseous pressure fromsaid supply to shift said element between said positions; gas passagemeans from said supply connection means through said valve to either endof said chamber, the reciprocation of said valve causing alternate flowto either end of said chamber in its alternate positions with shiftingthereof; and pressure build up regulating means in said gas passagemeans allowing time control of pressure build up sufiicient to shiftsaid piston means and valve element.

21. A pneumatically operated, pneumatically controlled system,comprising: fluid responsive means; a pneumatically operated timingcontrol valve; gas supply connection means to said valve; controlled gaconduit means from said valve to said fluid responsive means; and saidvalve including a valving element shiftable between a first positionallowing gaseous flow from said supply connection means to said fluidresponsive means, to a second position allowing exhaust from said fluidresponsive means to the atmosphere; piston means contained in a pistonchamber and connected to said element, bing responsible to gaseouspressure from said supply to shift said element between said positions;gas passage means from said supply connection means through said valveto either end of said piston chamber, the reciprocation of said valvecausing alternate flow to either end of said chamber with shiftingthereof; pressure build up regulating means in said gas passage meansallowing time control of pressure build up sufiicient to shift saidpiston means and valve element; said controlled gas conduit meansincluding restriction control means to maintain the time constant ofpressure increase in said fluid responsive means to at least about 0.15second for build up to within (1/ a) th of stable pressure.

22. A pneumatically operated, pneumatically controlledsystem,comprising: a pneumatically operated timing control valve; gas supplymeans to said valve; controlled gas conduit mean through said valve tosaid fluid responsive means; said valve including a valve elementshiftable between a first position allowing gaseous flow from saidsupply connection means to said fluid responsive, to a second positionallowing exhaust from said fluid responsive means to the atmosphere;piston means contained in a piston chamber and connected to saidelement, being responsive to gaseous pressure from said supply to shiftsaid element between said positions; gas passage means from said supplyconnection means through said valve to either end of said pistonchamber, the reciprocation of said valve causing alternate flow toeither end of said piston chamber, the reciprocation of in its alternatepositions with shifting thereof; and pressure build up regulating meansin said gas passage meant allowing time control of pressure build upsufiicient to shift said piston means and valve element; and manuallyshiftable, pneumatic valve switch means in said gas passage means andsaid gas supply means, shiftable between a first position allowing thegas pressure to operate said valve element in both directions, and asecond position allowing manual operation of said valve element.

23. The apparatus in claim 22 wherein said valve switch in said secondposition allows reduced pressure actuation of said valve element in onedirection and prevents pressure actuation of said valve element in theopposite direction to require manual shifting thereof.

References Cited UNITED STATES PATENTS 2,071,215 2/1937 Petersen 128283,013,531 12/1961 Mueller et al. 3,160,486 12/1964 Busch 137-624. 14 X3,209,748 10/1965 Thomas 128-53 3,219,031 11/1965 Rentsch 128283,277,887 10/1966 Thomas 12853 3,291,124 12/1966 Jennings et al. 12853FOREIGN PATENTS 673,551 3/1939 Germany. 673,551 3/1939 Germany 12853 L.W. TRAPP, Primary Examiner.

